• Korean Journal of Food Science and Technology
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• v.37 no.4
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• pp.532-536
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• 2005

GC-NPD analysis was performed on residues of aluminium phosphide in raw wheat and wheat products by trapping gaseous phosphine in the headspace of vessel. In Australian wheat, over 95% of samples were detected below 1 ppb, considered as safe level, whereas in American wheat, about 70% of 58 samples were detected within 1-10 ppb with 4 showing over 10 ppb. About 14-22% phosphine residues of raw wheat were retained after milling process. Wheat samples of same origin showed significant varying levels of phosphine.

• Microbiology and Biotechnology Letters
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• v.42 no.2
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• pp.177-183
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• 2014

Recently, many biofuels and chemicals converted from renewable resources have been introduced into chemical industries. Sargassum fulvellum is a brown macro-algae, which is found on the seashores of Korea and Japan. In this work, the production of total reducing sugar and levulinic acid from S. fulvellum, using dilute-acid catalyzed hydrothermal hydrolysis and statistical methodology, was investigated. As a result, 15.28 g/l total reducing sugar was obtained under the optimized conditions of $160.1^{\circ}C$, 1.0% sulfuric acid, in 20.2 min. Furthermore, 2.65 g/l levulinic acid was obtained at $189.5^{\circ}C$, 2.93% sulfuric acid, in 48.8 min.

• Journal of Korean Society of Environmental Engineers
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• v.38 no.6
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• pp.329-333
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• 2016

Disinfection by electrolysis would be useful for small wastewater treatment plant, combined sewer overflow, ballast water, swimming pool, and fish farming, where the transport, storage, and the use of chlorine gas is limited. This study investigated the feasibility of the electrolysis of dilute hydrochloric acid (HCl) for disinfection. The effects of HCl concentration, voltage and reaction time on the generation of oxidizing agents, HOCl, $O_3$, and $H_2O_2$, were examined in a series of batch test. The highest current efficiency was 99.3% which was found at 2.2%, 3 V, and 5 min of HCl concentration, voltage, and reaction time, respectively. Continuous electrolysis at 2.2% HCl, 3 V, and 5 min of the hydraulic retention time showed 97.4% of the current efficiency. Addition of sodium chloride up to 20 g/L linearly increased the oxidizing agents production. 92.2% of total coliforms were removed by the contact with the electrolyzed water.

• Clean Technology
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• v.17 no.2
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• pp.156-165
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• 2011

The process for bioethanol production from lignocellulosic biomass was studied through process simulation using PRO/II. Process integration was conducted with concentrated acid pretreatment, hydrolysis process, SMB (simulated moving bed chromatography) process and pervaporation process. Energy consumption could be minimized by the heat recovery process. In addition, material and energy balance were calculated based on the results from the simulation and literature data. A net production yield of 4.07 kg-biomass and energy consumption value of 3,572 kcal per 1 kg ethanol were calculated, which is indicating that 26% yield increase and 30% energy saving compared to the bioethanol production process with dilute-acid hydrolysis (SRI report). In order to make it possible, sugar conversion yield of cellulose and hemi-cellulose is to be reached up to 90% and fermentation of xylose needs to be developed. In order to reduce the energy consumption up to 30%, the concentration of acid solution after being separated by 5MB should exceed 20%. If acid/sugar separation by SMB process is to be practical, the bioethanol process designed in this study can be commercially feasible.

• Journal of Korean Society of Forest Science
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• v.41 no.1
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• pp.1-6
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• 1979

1. The study was conducted on the optimum condition of the treated substrate with dilute sulphuric acid solution and cellulase for saccharification. The wood (saw dust) of Alnus hirsuta Rupr. (10~15 years) was treated with 0.3%, 0.6%, 0.9%, 1.2%, 1.5%, $H_2SO_4$ solution at $1.5kg/cm^2$ for 15min., 30min., 45min., and 60min., followed by thermal treatment at $190^{\circ}C$ for 30min., and screening with 60 mesh sieve, after which to 0.5 grams of each sample was added 0.5ml cellulase solution, and 50ml 0.1M acetic acid buffer solution (pH 5.0), after incubating at $40^{\circ}C$ for 96hr. 2. The crude cellulase of Trichoderma viride Perx. ex. Fr. SANK 16374 was produced by the submerged culture process and produced in the culture fluid was salted out quantitatively by the use of ammonium sulfite. 3. Reducing sugar was determined by the 3.5-dinitrosalicylic acid (DNS) method. 4. The reducing sugar was increased with increase of the sulphuric acid concentration and saw dust was treated with 1.5% $H_2SO_4$ solution at $1.5kg/cm^2$ for 45min. showed the best saccharification (16.0%). The reducing sugar formation did not show statistically significant in 5% levels by thermal treatment time 45min. and 60min. 5. The substrate for cellulase which was treated with 0.9% $H_2SO_4$ solution at $1.5kg/cm^2$ for 60min. showed the best reducing sugar formation (23.6%). And did not show significant difference in 5% levels at 0.9%, 1.2%, and 1.5% $H_2SO_4$ solution.

• Korean Chemical Engineering Research
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• v.50 no.1
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• pp.141-148
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• 2012

In order to study the utilization of brown seaweed Laminaria japonica as an alternative renewable feedstock for bioethanol production, the properties of acid hydrolysis and ethanol fermentation were investigated. The acid hydrolysis enhanced the final yield of fermentable sugars, which led great increase of ethanol productivity. The maximum yield of reducing sugars reached 135 mg/g-dry Laminaria japonica after 1.0N sulfuric acid-hydrolysis at $130^{\circ}C$ for 6 h. The Saccharomyces cerevisiae (ATCC 24858) could ferment $C_6$-sugars like glucose, galactose and mannose into ethanol, but not $C_5$-sugars like arabinose and xylose. Optimal fermentation time varied with sugars; 48 h for glucose, 72 h for galactose, and 96 h for mannose. Nevertheless, the ethanol yield from the hydrolysate reached 242 mg/g-dry Laminaria japonica after fermentation by the S. cerevisiae at $35^{\circ}C$ for 96 h, which corresponds to approximately 4 times more than the theoretical yield from total reducing sugars in the hydrolysates. It indicates that the non-reducing sugars or oligosaccharides dissolved in the hydrolysate played an important role in producing bioethanol. The ethanol concentration linearly increased from 2.4 to 9.2 g/L, while the ethanol yield per dry weight of biomass decreased from 242 to 185 mg/g, with increasing the ratio of biomass to acid solution from 1 to 5% (w/v). The bioethanol yield estimated was approximately 7,400~9,600 kg/ha/year, and indicated that Laminaria japonica is a promissing feedstock for bioethanol production.

• Journal of the Korean Chemical Society
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• v.23 no.6
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• pp.358-367
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• 1979

EHT and CNDO/2 calculations have been performed to determine conformations of acetamides and diacetamides, and of their protonated forms. Results show that: protonation is always favored on the cis position with respect to N due to greater attractive potential between $H^+$ and N; the trans-trans conformer of diacetamides gives the most preferred protonated form although the cis-trans conformer is the most stable one for the unprotonated diacetamides. Protonation on a carbonyl oxygen is predicted to increase both charge and orbital controlled $S_N$SN reactivities of the protonated carbonyl carbon due to increases in positive charge and AO coefficient of ${\pi}$-LUMO of the carbon atom. In the acid catalyzed hydrolysis of diacetamides therefore it appears highly probable that the rate determining attack by a water molecule occurs at the carbon of the protonated carbonyl group and the carbonyl carbon-nitrogen bond scission follows subsequently. This mechanism is consistent with that generally accepted for the hydrolysis of amides in dilute acid solution but disagrees with that proposed by Laureut et al., for acid hydrolysis of N-acetyl-lactams.

• Korean Chemical Engineering Research
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• v.52 no.6
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• pp.789-795
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• 2014

Acetic acid is the most abundant and serious ethanol fermentation inhibitor in dilute-acid hemicellulosic hydrolysates. A mixture of xylose, acetic acid and sulfuric acid was chosen as a simulated hemicellulosic hydrolysate so as to find an optimal separation system to selectively remove acetic acid from the hydrolysates. In order to attain the purpose, emulsion liquid membrane was applied to removal of acetic acid from the simulated hemicellulosic hydrolysate. The effects of main constituents of water-in-oil (W/O) emulsion, such as amine extractant type, surfactant composition, additive type, and type and concentration of stripping agent, on extraction of acetic acid, xylose, and sulfuric acid in the simulated hemicellulosic hydrolysate were investigated. Under specific experimental conditions, degree of extraction of acetic acid was higher than 95% while loss of xylose was insignificant, which means that the current emulsion liquid membrane can be an economically feasible process.

• Applied Chemistry for Engineering
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• v.4 no.4
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• pp.683-691
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• 1993

All the activities and physical properties including surface tension, foaming power, foam stability, emulsifying power, dispersion effect, wettability and solubilization of sodium dodecyl polyoxyethylene ${\alpha}$-sulfo alkanoates aqueous solution were measured and critical micelle concentration was evaluated. Their cmc ebaluated by the surface tension method was $10^{-4}{\sim}10^{-5}mol/{\ell}$, and surface tension of the aqueous solution was decreased to 30~70dyne/cm. The experimental results for foaming power, foam stability, emulsifying power in benzene or soybean oil, dispersion effect in calcium carbonate, wettability and solubilization showed a good and efficient surface active properties, and then it would be expected that these products could be applied as O/W type emulsifier, dispersion agent.

• Microbiology and Biotechnology Letters
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• v.37 no.3
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• pp.226-230
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• 2009

Rice straw was pretreated using dilute sulfuric acid at reaction conditions covering two levels of reaction temperature (140, $150^{\circ}C$) and five levels of acid concentrations ($1.0{\sim}3.0%wt$). The production and decomposition rates of major components of rice straw indicating glucose, xylose, galactose and arabinose were investigated. The production rate of arabinose and the decomposition rate of xylose were greatest among them. The maximum attainable hemicellulose (xylose+galactose+arabinose) yield was about 80%. High acid concentration appears to favor the maximum yield but high temperature does not. The optimum condition was found to be $140^{\circ}C$, 2.5% and 20 minutes. The maximum glucose yields were almost same, around $16{\sim}18%$, regardless of reaction conditions.